Detect presence of mass ring after questionable recone?

[mfaughn]

I'm wondering if there is any way to determine if the mass ring was installed without removing the dust cap. I have a set of 136A that were reconed with 2235 cones. Whoever did it used wildly inappropriate surrounds so it makes me question whether or not they installed the mass rings. FWIW, I've removed the (stiff rubber) surrounds with less than expected damage to the cones and I'm going to install proper surrounds to just to see what my speakers are sorta supposed to sound like.

[Robh3606]

OK assuming they are the correct cones all you need to do in look at the driver FS. S/B around 20Hz +/- 10%

Rob

[Mr. Widget]

OK assuming they are the correct cones all you need to do in look at the driver FS. S/B around 20Hz +/- 10%

Rob

That was my first thought too, but if the surrounds are wrong any FS measurements will be a guess at best.


Widget

[Earl K]

I'm wondering if there is any way to determine if the mass ring was installed without removing the dust cap. I have a set of 136A that were reconed with 2235 cones. Whoever did it used wildly inappropriate surrounds so it makes me question whether or not they installed the mass rings. FWIW, I've removed the (stiff rubber) surrounds with less than expected damage to the cones and I'm going to install proper surrounds to just to see what my speakers are sorta supposed to sound like.

At full Xmax excursion ( X-Mech actually ) the ring will contact the inner top-plate ( pole-piece ) and make a "KLANKING-Sound" as it smacks that top-plate. All this according to our long-lost Giskard.

A tone generator set 20hz ( or lower ), an amp, and some applied voltage should get the cone pumping enough to ferret out the situation.

Since the surrounds need replacing ( for better looking original types ), one need not worry if you rip them up in the process.



PS: I think X-Mech ( which is a peak to peak number ) is around 22mm ( so, 22mm/2 gives 11mm, which sounds about right )

[Robh3606]

That was my first thought too, but if the surrounds are wrong any FS measurements will be a guess at best.


Widget

Hello Widget

I have re-foamed a couple pairs and if he get's it from Looney Tunes as a example Fs is correct right after the glue dries.

Rob

Hello Earl

He already took off the wrong surrounds. Yeah that will work but I would try Fs first. Ever run a pair hard enough to smack the ring??? I have as LFE subs you don't want to do that as it stresses the hell out of the driver.

Rob

[Earl K]

Hello Widget

I have re-foamed a couple pairs and if he get's it from Looney Tunes as a example Fs is correct right after the glue dries.

Rob

Hello Earl

He already took off the wrong surrounds. Yeah that will work but I would try Fs first. Ever run a pair hard enough to smack the ring??? I have as LFE subs you don't want to do that as it stresses the hell out of the driver.

Rob

Hi Rob,

I'll need to defer to your greater experience here ( that "Looking-for-KLANK" is a very bad idea ).

Earl

[mfaughn]

Thanks, y'all. I'll install the surrounds (on their way to me now from Rick Cobb) and then measure Fs. If I understand correctly, without the mass ring I should essentially have a 2234 (albeit with an alnico magnet motor) vs a 2235. The diff b/w these for Fs is 23Hz vs 20Hz. It'll be interesting to see what I get and also how close each driver is to the other.

[toddalin]

Any big JBL woofer will "klank" if given enough power at too low a frequency. I found this to be the case when trying to push 130As a bit too hard, and they have no mass rings.

The best way to tell would be to run something like Woofer Tester and look at the T/S parameters.

[mfaughn]

The best way to tell would be to run something like Woofer Tester and look at the T/S parameters.

I had one of those...and sold it. I thought I was done fooling with speakers. Silly me...there is no escape.

[short_circutz2]

Thanks, y'all. I'll install the surrounds (on their way to me now from Rick Cobb) and then measure Fs. If I understand correctly, without the mass ring I should essentially have a 2234 (albeit with an alnico magnet motor) vs a 2235. The diff b/w these for Fs is 23Hz vs 20Hz. It'll be interesting to see what I get and also how close each driver is to the other.

2234 IS a 2235 without the mass ring, whether or not it's an AlNiCo or ferrite motor. With a 2234, you'll have higher sensitivity in the lower midrange/mid bass.

[mfaughn]

2234 IS a 2235 without the mass ring, whether or not it's an AlNiCo or ferrite motor. With a 2234, you'll have higher sensitivity in the lower midrange/mid bass.

That's what I've read here. This site is such a wonderful resource! I've also read that some folks prefer the 2234 in the L300, which is what they are in. I just would like to know what I've got either way.